Wx Maxima output format

Question

What do the thick solid vertical bars just outside the parentheses represent. See the screen grab of a wx maxima output

See also here, the input and output.:

note: this only occurs sometimes. Other times the bars do not appear. Are they just redundant?

Answer 1

those "bars" are actually the crossing ends of large upper- and lower-half-parentheses. As such, they are not significant, they just mean maxima is not trying to be too clever with fonts and typesetting.